β-半乳糖苷酶/β-Galactosidase

β-半乳糖苷酶

β-Galactosidase

from E. coli overproducer

General description

β-Galactosidase or β-D-Galactoside galactohydrolase is basically a tetramer made up of identical four polypeptide chains, each constituting 1023 amino acids. It is very specific for D-galactose and requires K⁺ or Na⁺ and Mg²⁺ to be fully active. β-Galactosidase enzyme with an oxygen glycosidic bond catalyzes reactions with β-d-galactopyranosides.

Specificity

切割单糖、寡糖或糖肽的1,4-连接末端半乳糖残基。

Application

β-galactosidase has been used in enzyme-linked immunosorbent assay (ELISA). Use β-Galactosidase to produce a calibration curve in enzymatic assays.

Quality

污染物：GIDH、GPT、LDH、MDH和草酰乙酸脱羧酶，每种污染物含量均<0.01％

Physical form

悬浮于3.2 M硫酸铵溶液中，pH约为6，晶体状

Preparation Note

硫酸铵制剂可以在2至8℃下稳定保存至标签注明的失效日期。可直接用于大多数应用，如乳糖的定量。

在不存在硫酸铵时，应使用Mg²⁺ (89 mM)和硫醇试剂（1mM β-巯基乙醇，1 mM二硫苏糖醇）稳定β-半乳糖苷酶溶液[Beutler，1984]。硫醇可以减缓由分子内二硫键引起的酶二聚体形成。

活化剂：需要K（50 mM）进行激活（乳糖水解）。